System of speed control for induction machines



R. E. HELLMUND. V sYsTEM OF SPEED comm FOR mouc'now MACHINES.

APPLICATION FILED AUG-10,1918. 1 ,425 ,652; v Patented Aug. 15, 1922. Y

3 SHEETS-SHEET I.

WITNESSES: INVENTOR R. E. HELLMUND.

SYSTEM OF SPEED CONTROL FOR INDUCTION MACHINES.

APPLICATION FILED AUG.IO, X918.

1,425,652, Patented Aug. 15, 1922; 3 SHEETS-SHEET 2- W I I In will a Q! a I l l 1! l WITNESSES: INVENTOR R. E. HELLMUND. SYSTEM OF SPEED CONTROL FOR INDUCTION MACHINES.

APPLICATION FILED AUG. 10, 1918/. 1,425,652, Patented Aug. 15, 1922.

3 SHEETS-SHEET 3- WITNESSES: INVENTOR Q/JWM BY U TED ,nUnoLr n. HELLMUND, or swIssvALn, iENNSTLVANIA, s'sronon To HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or renn- SYLVAN IA.

PATENT orru naz.

I SYSTEM or srEEn oon'rnoL non INDUCTION MAenmns.

. Specification of Letters Patent. Patgf ted Aug, 151,

Application filed Au ust 10, 1918. Serial Na 249,333.

I 0 all whom it may concern I Be it known that I, RUnoLr E. HELLMUND, a cltizen of the German Empire, and a resident of S wissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and. useful Improvement in Systems of Speed Control for IIIClL1.Ci11OI1l\I2I- chines, of which the followingis a specification My invention relates to systems of speed control for induction machines when operating as motoring or as recuperating machines, and ithas for its object to provide a system of the type designated which shall permit operation at a number of running speeds and at relatively high eiliciency, together withconveuient transition means for passingfrom one speed to another.

In the accompanying drawing Fig. 1 is a diagrammatic view of a pair of induction motors, togetherwith supply and control circuits, and other auxiliary apparatus embodying one form of my invention; Figs. 2 tov 6, inclusive, are simplified diagraminatic views illustrating the connections shown in Fig. 1; and '5' is a view, similar to Fig. 1, and illustrating a modification of my invention ii In the application of induction motors to industrial uses, as, for example, in railway work, it is usual to employ induction inotors in pairs, obtaining substantially onehalf synchronous speed bycascade operat on and substantially synchronous speed by direct connection to the line. It is frequently desirable to obtain .an intermediate speed of three-fourths synchronism and, to, this end, I find that a smallauxiliary induction machine may conveniently be operated at substantially one-half its synchronous speed and the secondary windings of the main motors may thereupon beconnected to the prinnary and secondary windings of said auxillary machine. Under these conditions,

ondary members, thereof may be transmitted through the auxiliary machine and returned to the source or otherwise utilized.

By reversalof the phase sequence between the auxiliary machine and the main ma.

chines, a speed increment of substantially speed, these two desirable additional speeds being obtainable with an auxiliary machine I having a 1 capacity of substantially onee ghth 0f the two motors at a relatively high speed.

Referring to the drawing for a more detailed understanding of my invention, I show a pair of mam nduction motors at 1.0

and 11 in Fig. 1, each motor being provided with wound secondary rotors terminating in slip rings .12 and 13, respectively, and further being coupled to driving wheels, as

shown at 14- 14. i 1

Energy for the operation of the motors 10 and 11 is shown as derived from a singlephase trolley 15, passed through atr'ans-m former 16 and converted into polyphase current by a suitable converter l7,shown as of the well known asynchronous type."

minals 21 at the other end thereof. In like manner the secondarywinding of the machine 18 is provided with slip ring terminals 22 at one end thereof and with slip ring terminals 23 at the other end thereof. Suitable liquid rheostats 24 and 25 are connected to the terminals 21 and 23, re'spectively, The machine 18 preferably hasonehalf the number of poles of the machine 17, whereby the machine 18 runs at substantially one-half synchronous speed. The primary rectly to the converter 17 and the primary terminals of the motor 11 may be similarly connected through closure of a suitable switch 26. The secondary terminals 12 of inary terminals 20 of a machine 18 through a phase-sequence reversing switch 81 and a switch 28 and, in like manner, the secondary terminals 13 of the motor 11 may be conterminals of the m'otorlO are connected di-,

the motor 10 may be connected to the prijnected tothe terminals 22 of the machine 18 through a switch 32. y

The secondary terminals l2 of the machine 10 may be connected to the primary terminals of the machine 11 through a suitable switch 27, and the primary and secondary winc'lings oi. the machine 18 may be respec' tively short-circuited by suitable switches 29 and 30, thus connecting the rheostats 2-iand 25 directly to the secondary windings of the main motors, respectively.

The switches 26 to 32, inclusive. may he i any desired type, either manually, pneumatically or electromagnetically operated. the specific type cl switch JFQPlONQtl forming no part oil the present invention. in l, the switches are shown as olf the elcctromap netic type, being subject to the control oil a manu ally operated controller 33 having five positions indicated as A? to ill, inclusiv'e.

Having thus'described the arrangement of a system embodying invinveution, the operation is as follows. Upon moving the controller 33 to the position A, the switch 27 is closed to connect the main machines in cascade and to further connect the auxiliary machine 18 in cascade therewith all as indicated in Fig. 2, the energy flow being as indi cated by arrows. By this arrangement, a speed considerably undero1'1ehalt synchronism may be secured and said speed maybe gradually raised to substantially one-l1alt syi'ichronism by manipulation of the rheostat The controller is next moved to the position. B to close the switch 30 and eliminate the machine it? from the active circuit, producing the simple concatenation connection of Fig. 3 and giving the maximum concatenation speed of substantially onehalf synchroi'ious speed.

The controller 33 is 1183.; moved to the position C to open the switches 27 and 30 and close the switches 90 and wherephase-reversing sequence MA) upon the primary windings of both main motors are connected directly to the source and the secondary winding of the motor 10 is connected to the stator winding oi? the machine 18, whereas the secondary winding of the machine ll is connected to the rotor 'ivindinus oil the machine 18, all as indicated in F 4;, both the resistors SZeIJa-nd 25 also being in circuit. The machine 18. having substantially oi'ied'ial'f the number of poles of the machine 17. tends to produce a total frequency, i. e... sum of stator and rotor 'lrequencies, of substantially one-half oil the si'lpply frequency. Since the machines 10 and 11. run at about the same speed. their secondary frequencies must. be about equal. Since, furthcr. the sum of the secondary frequencies is our-halt line lrcquei'icy, each. i'n'ust be about one-fourth line freipioncv, with resistance cut out. li hilc resistance is incircuit. the action of the rheostats 2st and 25 is reflected haclr through the machine 18,

however, to the secondary members of the machines 10 and ll, causing: more slip therein than would otherwise be the case and permitting operation, for example, at liveeighths oi? syi'ichronous speed. The resistors and are thereupon gradually reduced in value until a running speed of threetourths synclntonism is secured.

The controller 33 next moved to the position *D, closing the switches 29 and 30. shunting both the stator and rotor windings out of circuit and connecting the machines i and ll. directly to the resistors 24 and 25. aid resistors having been increased in value. operation at slightly above threetourths s nclironism may be secured, and the gradual elimination ol' the resistors 24 and now brings the main machines to syn'cl'ironism minus slip or substantially simtzlironisui, as indicated in Fig. 5.

' it orcr-synchronous operation is desired. the controller 33 is next moved to the position l to open the switches 27 and 30 and to reverse the phase sequence between the machines 10 and .18 and ll and 18, respectively. by encrgization oi" the switches 31 and Under these conditions, the substout i a ll y l rotating one-tonrtn-lrequency field SUDl'JllGCl by the machine '18 to the secondary members oi the motors- 10 and 11.

"s in opposition to the stator fields therein causing; the main machines 10 and 11 to run at ynchroi'io'us speeds, energy being tran nitted trom the machine 17, through the siLa'lt 9. to the machine 18 for supply to the ainanotor secondary members, as dislincj'uished from the operation of Fig. 4, wherein energy flows from the secondary members of the main motors through the mmihine and returns to the supply.

ll'hile l have described my invention only in connection with motoring operation, it will be obvious to those skilled in the art that the dill. -.nt connections thereof are equally suscept tie of application in connection with .;eneration.

in the system of Fig. l, the machine 18 is indicated as being driven by the converter but it occasionally happens that the conrortcr is not available or has not sufficient rapac ty to drive said machine and. under t conditions, the machine may be rendered scll d'riving, as indicated in Fig. 7. .2 pair o! main motors l0 and 11, as before, derive their energy from a three-phase supply systei'n l0. An auxiliary machine 18 is employed having a double-wound stator member 4-1 and a double-wound rotor membrr said double windings being of the torn; employed for imparting two different pole numbcrstoa winding, as in the internal cascade motor. Energy is derived from the source 40 through a suitable transformer and is supplied to the mid-points of opposite siil it the respective phase divisions terminals of said two windings, whereupon.

of the stator 4:1, as indicated. correspofid ngppposite" points, of the respective by its higher pole number. The rotor terminals12 and 13 of the machines 10 and 11 areconnecte'd, respectively, to corresponding terminals of the stator. and rotor Windings 4i and 42, and the resistors 24 and 25 are similarly connected tofthe remaining the machine 18 functions in accordance with its low pole number,,as does the machine 18 OfFlgQl.

Throughout this specification, I have dd scribed my invention as embodied. in an auxiliary machine operating at substantially one-half its synchronous speed, thusimpart- .ing one-fourthsynchronous speed to the rot ating fields imparted to the main secondary circuits, Obviously, other relative frequenones may be developed in the aux llary machine, resulting in the production of onesixth or any other desiredhportion of said f qu n i 'th e nda y m ers of t saiduiachines. i L i a M i i While I have shown myvinvention in two of its preferredforms, it will be obvious to those skilled in the art that itisnot so vlimited butis suscept ble of;v still other m nor; ycqnnerctqddircfly to Said im t the 'Changgs and mo'dlficatwns WlthQut' depart" secondaryfieldsof said main motors rotate its fr m t r ri rthr etf nd T s e, therefore that only, such limitations shall hei lacerl thereupon as are imposed bv, the prior art orare specifically set forth inthe app d d c a ms.

' I claim as my invention: v

1., The-combination with asource of alterhating currenhfof two main induction mas, an, aux a y ,ind ticn machin dying ndep nd nt P ima yvar BCQllClary windings, means; for connecting the prieating the sec- Qnd ry i ding .efse i mai m hi es to 'sil ed of'said aux ry ma ine- 1 Z JThe combination with sourcerof al mach nes, an aux l y induction machine,

mat crconnetinsithe prima y ndings Ofid main mac i s t a d vsou tle mean for connecting the secondaryiwindings of sa main machin s the prima y d cu le y mncbng i id auxlhary mach re pect vely, mean indep nden of sai 0 means for sisefthe. speed of a d au ilmaam currents supplied to said auxiliary machine.

3. The combination with a source of alternatlng current, of two main inductlon machines, an auxiliary, induction machine,

means for COI1I1BCtl11g tl1G primary windings of said main machine to said source, means auxiliary machine at of its speed, if connected directly to said source, so that the secondary, field of said mainmotors rotate co-directionally with the primary fields there'ofl whereby a speed o'lisubstantially under synchronismyis imparted to each of, said mainmachines.

4/ The comhinationwith a source'of alternatlng current, ,oftw o main inductloninachines, an auxiliary induction i machine, means. for connecting the primary windings of said main machine to said source, means for connecting the secondary windings of said main machine to the primary and sec- "ondary, windings, respectively, of said auxil ary mach ne, and means for drivmgsaid auxiliarymachine at of 'its speed, if

Jo-directionally with the primary fields of saidmain machinesjand means for independently ad ustlng the-currents supplied .trom sald main machines to sa1d auxil1ary machine." i

5. The combination with a source of altermung current, of two main induction mamay), windingagf said mam ac to chines f an pauXliia-lythllldllplilon acr11ie, said. Source; means m means. or COIHIGCYIDQ e primary wln lugs of said main machine to said source, means 1 fofcorinecting the secondary windings of said ma n machines to the primary and secondarywindings, respectively, of said auX- iliaryimachi ie, and means for driving said of its, speed, if connected[directly to said source, s'o'thatthe s'eco ndary'fields of sa d main motors are "in aux lia y ac n at v o'pposition the primary fields thereof, matisg c rr t 9 mums in ct on speed of substantially over 6. Thecombi'na ion with asource of alter- W under synchronism is "imparted'to each a ng curre t t mainf nd fie m chines, an auxiliary induction machine,

means o 'l ons e na h P m ry wind ng i H 4 Q1": Sed a t 'me h io sa dsQu a-Ine s la yn eal-nae, andmeans fo vad ustmgj he fexicon ectmg the se ond ry winding of so iliary machine at 7h of its speed, 1f con.-

nected directly to said. source,so that the secondary fields of said main, motors rotate in opposition to the primary fields thereot,

Y 1. whereby a speed of substantially over synchronisin is imparted to each oi said main machines, and means for independently adjusting the currents supplied from said main machines to said auxiliary machine.

7. The combination with a source of alternating current, oi a phase-converter of the dynamo-electric type connected thereto, whereby polyphase alternating currents may be derived from said source, two main induction machines and an auxiliary induction machine, said auxiliary induction machine beingmeehanically coupled to said phase-converter and being driven thereby ,at a speed other than its substantially synchronous speed, it connected directly to said source, means for supplying said polyphase alternating currents to the primary windings of said main machines, and means for connecting the secondary windingsof said main machines to the primary and secondary windings, respectively, of said. auxiliary macliine,'\vhereby said main machines are caused to operate at speeds other than their inherent synchronous speed minus slip, as determined by the frequency of said source. I I

8. The combination with a source of alternating current, of a phase-converter of the dynamo-electric type connected thereto, whereby polyphase alternating currents may be derived from said source, two main induction machines and an auxiliary induction machine, said auxiliary induction machine being mechanically coupled to said phase-converter and being driven thereby at a speed other than its substantially synchononous speed, it connected directly to said source, means for supplying said,

polyphase alternating currents to the primary windings of said main machines, means connecting the secondary windings of said, main machines to the primary and secondary windings, respectively, of said auxiliary machine, whereby said main machines are caused to operate at speeds other than their inherent synchronous speed minus slip, as determined by the frequency of said source, and means for varying thecurrents flowing between said main machines and said auxiliary machine.

9. The combination with a source of alternating current, of a phase-converter of the dynamo electric type connected thereto, whereby polyphase alternating currents may be derived from said source, two main induction. machines and an auxiliary induction machine, said auxiliary induction machine being mechanically coupled to said phase-converter and being driven thereby at substantially one-halt its substantially synchonous speed it connected directly to said source, means for supplying said polyphase alternating currents to the primary windings oil. said main machines, and means for connecting the secondary windings oi" said, main machines to the primary and secondary windings, respectively, of said auxiliary machine, whereby said main machines may be caused to operate at substantially three-fourths or substantially fivefourths of tl'ieirinl'ierent synchronous speed minus slip, determined by the frequency of said source. I

10. The combination. with a source of alternating current, of a phase-converter of the dynamo-electric type connected thereto, whereby polyphase alternating currents may be derived from said source, two main induction machines and an auxiliary induction machine, said auxiliary induction ma chine being mechanically coupled to said phaso-converterand being driven thereby at substantially one-half its substantially synchronous speed it connected directly to said source, means tor supplying said polyphasealternating currents to the primary windings'o't said main machines, means for connecting the secondary windings of said.

main machines to the primary and secondary windings, respectively, of said auxiliary machine. whereby said main machines may be caused to operate at substantially threetourths or substantia ly fivefourths of their inherent synchronous speed minus slip, as

determined by the frequency ofsaid. source, and means for varyin the currents flowing between said main machines and said auxiliary machine.

11, The combination with a source of alternating current, of two mainpolyphase indiliction dynamo-electric machines, anauxiliary polyphase induction-type dynamoelectricmachine, means for driving said auxiliary dynamo-electric machine, at a speed radicall difierent from its inherent synchronous speed, as determined by the frequency of said source. means for connecting the primary windings of said main machines to saidfsource, means for connect ing the secondary windings of said main machines to the primary and secondary windings of said auxlliary machine, respect vely, and means for reversingthe phasesequence between said main machines and said auxiliary machine.

12. The combination with a sourceot alternating current, of two main polyphase induction dynamo-electric machines, an auxiliary polyphase induction type-dynamo electric machine, means for driving said machines to the primary and secondary r the current flow between said main machines mam auxiliary dynamo-electric machine at speed radically different from its "inherent synchronous speed, as determined byi' th'e frequency of said source, means for con 'necting the primary windingsof'sa1dma1n inachinesto said source, means for connect mg the secondary windings of said mam Windin'gsof said auxiliaryanachine re'spec tively, means for reversing the phase-S19 quence between said maini machines and said auxiliary machine, and means for adjusting and said auxiliary machine, g V

13. The combination with a source 01" all ternating current, of two maininductiont machines, an auxiliary induction hine embodying relatively rotatable primary and secondary windings, means for connecting the primary windings of the main machines to said source, and means for connecting the secondary windings of the main niachines to the primary and secondary wind-v ings of the auxiliary machine, respectively,

in such manner that the auxiliary machine either delivers electric energy to both olthe main machines or absorbs electric energy from both of themain machines.

14. The combination with a source of alternating current, of two main induction machines, auxiliary induction means embodying a plurality of windings, means for connecting the primary windings of the main machines to said source, and means for connecting the secondary windings of the main machines to diflterentwindings of the auxiliary induction machine, respectively, in such manner that the auxiliary machine either delivers electric energy .to both of the main machinesor absorbs electric energy from both of the main machines.

15. The combination with a source of alternating current, of twovmain induction machines, an auxiliary induction machine embodying relatively rotatable primary and secondary windings, means for connecting:

the primary, windings of the main machines ternating current, of two main induction machines, an auxiliary induction machine, means for connecting the primary windings of said main machines to said source, means for connecting the secondary windings of said. main machines to the windings of said auxiliary machine, means independent of said connections for fixing the speed of said auxiliary machine,andirieans forfadjusting" the currents supplied to' said auxiliary machine, i i i i "17. The combination with a source of a1:

tr'natind current, o'iltwdinain induction machines, an auxiliary lnducti'onmachine, means for connecting the vprimary wind ngs of said main machines to said source, r'ne'a'ns tor connect ng thesecondary windings of said-main mach lugs of "said a pendent ct irfes to different windirxilriry machine, means inliary machine. V

18; The combination with two 'main incan; ninacl1iries having "primary and secondary .windings, "means" for connecting ins-ting the currents supplied to said said" primary windings inpara'ner relation,

an.- induction machine having primary andsecondary windings; said lastmentioned primary and secondary windings being connected, respectively, to the secondwindings'of said main induction machines in such manner that said auxiliary machine tends to rotate at a speed corresponding to thesum of the speeds of rotaeed of said an. hairy machine, and means] tion of its primary and secondary fields, and i a translating device for interchanging mechani cal energy with said auxiliary machine andfor controlling the speed of the same.

19. The combination withtwo main induction machmes having primary and sec:

ondary windings,- means for connecting,

said primary windings in parallel relation, auxiliary induction-machine means lncludnected, vrespectively, to'the secondary Windings oi? said main induction machines in such manner that said rotor element tends to rotate at a speed corresponding to the sum of the frequencies in said secondary windings, and a translating device for intering wound stator and rotorelements cona changing mechanical. energy with said aux iliary means and for controllingthe speed of said rotor element. v I

20. The method of operating a pair of main-induction machines in coir unction with a. source of polyphase alternating current and. an auxiliary induction machine,

said auxiliary machine being driven at a speed other thanits synchronous speed, as

determined by the frequency of said source,

which comprises, at times, connecting the )rimar windin s of said main machines to l b said source and connecting the secondary windings of said main machines to the primary and secondary windings of said auxiliary machine, respectively, in such phase-sequence as to produce, under-synchronous operation of said main machines and, at other times, close-clrcuiting the secondary windings ofjthe main machines.

The method of opera-tinge pair of main induction machines in conjunction with a source of polyphase alternating current and an auxiliary induction machine, said auxiliary machine being driven at a speed other than its synchronous speed, as determined by the frequency of said source, which comprises, at times, connecting the primary windings of said main machines to said source and connecting the secondary windings of said main machines to the primary and secondary windings of said auxiliary machine, respectively, in such phase-sequence as to produce under-syncln-onous operation of said main machines and, at other times, reversing the phase-sequence between said main machines and said auxiliary machine, whereby said main machines are caused to operate at over-synchronous speed.

22. The method of operating a pair of main induction machines in conjunction with a source of polyphase alternating currents and an auxiliary induction machine, said auxiliary machine being driven at substantially one-half its synchronous speed, as de termined by the frequency of said source, which comprises, at times, connecting the primary windings of said main machines to said source and connecting the secondary windings of said main machines to the primary and secondary windings of said auxiliary machine, respectively, in such phase-sequence as to produce substantially threei ourths synchronous speed in said main motors and, at other times, reversing the phase-sequence between said auxiliary ma chine and said main machines, whereby said main machines are caused to operate at substantially five-fourths of synchronous speed.

In testimony whereof, I have hereunto subscribed my name this 31st day of July, 1918.

RUDOLF E. HELLMUND. 

